John Geloso was born in Argentina January 10th
1901, where his Italian parents had temporarily moved from Italy. The entire family
moved back to Savona Italy in 1904, where John studied at the nautical
school. After finishing school John started an electromechanical workshop where
he manufactured items he had personally patented. In 1920 he went to the U.S.,
and began working for Pilot Electric Manufacturing in New York and attending Copper
Square University. After graduation, in 1925 he was appointed chief engineer by
the Pilot president Mr.Isidor Goldberg who had realized the potentiality of that
young Italian.

John was able to solve most of the problems
affecting, at that time, the development of radio, such as receivers AC supply,
single command for frequency change, acoustic improvements, etc.

In 1928, in front of several scientists among which
Lee De Forest (the "father of radio") and Hugo Gernsback (the licensee of the
WRNY station), he demonstrated a system for images reproduction based
on a Nipkow disk with 44 holes, able to generate 36 lines and 15 frames per
second. Images were transmitted from a transmitter site at Hudson Terrace in Coytesville (NJ) to Philosophy
Hall (NY), on the wavelength of 326 meters, since pictures could not be properly
synchronized through the WRNY Hotel Roosevelt studios. Reception required a 24
inch scanning disc rotating at 240rpm. Eventually, Gernsback presented daily 5
minute programs in cooperation with John Geloso, via 48 line mechanical scanners
set up in Coytesville,

Below you can see John (on the left hand side) with his telecinematographic
equipment.

Here John holds one of the early photocells used for television
purposes, in company of Hugo Gernsback (center).

By 1929 he was deeply committed to the design of
the Pilot Super Wasp receiver, the first completely AC-operated
short-wave receiver in the market. John was mainly interested in the mechanical
aspects of replacing plug-in coils, commonly used at that time to achieve
multi-band operation, with a mechanism of highly ingenious construction based on
switches operated by cams.

In 1931 he returned to Milano, Italy for setting up its own
business.

The first Geloso radio I am aware of is model G.50, dated back
to 1932. It had five tubes, i.e. two RF amplifiers (UY235), one detector
(UY224), one audio power amplifier (UY247) and one rectifier (UY280).

At that time
home radios
were fairly pricey compared to an average wage and, to save money, it was then common to buy apparatuses in kit form
(most commonly NOT including a wooden cabinet, which one often
had to construct by himself...).

Some excerpts from the G.50 presentation:

" ... often some instability phenomena can
occur... (some guidance is then given on how to avoid instability) ... but if
the radio is too stable, then it will also be not too sensitive ..."

" ... hum will totally disappear increasing
the capacitor up to 8 microfarad, and this will be possible when electrolytic capacitors will
become available ..."

"... our sole ambition is to get soon
all necessary materials and components ..."

Looking at the G.50 schematic diagram, one can
see that, while paper
capacitors were measured in microfarad as done today, the RF capacitors (i.e.
the mica and the variable ones) were measured in centimeters (cm). Farad
belongs to the MKS measurement system, and centimeter belongs to the CGS
system. Below
you see the label of a 5,000 cm transmit mica capacitor of those years.

After some search, I have determined that 1 cm
is equal to about 1.1 pF, therefore the 5,000 cm capacitor actually has a
capacitance of about 5,500 pF.

By the mid-30ies, John Geloso S.A. had already become
an important home and professional electronics
manufacturer, representing one of the few alternatives to importing equipment from abroad.

Geloso was also building plain
components, such as switches, capacitors, potentiometers,
transformers, etc. (really made in Milan, not re-labeled Taiwan
stuff...); on the other hand autarky was one of key guidelines in
the fascist era.

Geloso was also active in the military field, as witnessed by this odd
circa-1935 transceiver working in the 50 - 56 MHz range.

The front panel is marked (in Italian) "Small radio box -
companion to a m/m-180 photophonic station". Before WWII "photophonic" stations
were used for short-range voice and "optical telegraphy" communications between
the military underground fortifications of the
Alpine Wall, over a
light beam that the enemy could hardly intercept. The radio link was alternately
used in case of fog or obstacles degrading the optical link quality. The small
transceiver employs a 4-volt direct-heating tube (a Zenith type RRBF, built in
Italy by FIVRE) working either as super-regenerative receiver or as self-oscillating
transmitter (AM + FM at the same time). Despite its low RF output power (around
250 mW) and its very broad and deaf receiver, I succeeded to work Trevor
G3ZYY in Cornwall UK on 50.370 MHz FM with fairly good signals, profiting of a
sporadic-E opening. Interesting to note that the RX/TX switch only changes the
grid resistor value, absolutely nothing else!

In 1934 the Geloso factory moved from its initial site of via Sebenico
7 to a new site in via Brenta 18 still in Milano, and in 1939 to a large plant
in via Brenta 29 (about 17,000 square meters).

After WWII, Geloso expanded the production of components
(electrolytic capacitors, microphones, piezo pick-ups, pre-adjusted receiver RF
groups, IF transformers, etc.) as well as of complete equipment, including a wide selection of radios, audio amplifiers, recorders, vinyl disk players,
etc.

Surely, the most popular Geloso product was
the tape recorder mod. G.255 which was introduced in 1957. Most Italian families
owned one of these.

Another important product line for Geloso were TV sets, B&W
of course. At that time they came in just a few screen sizes, i.e. 17",
21" and eventually 24". The price of a TV set was rather high; the console model shown below
costed 330,000 year-1954 lira, that correspond to about 4,100 year-2001 Euro
(currently 1 Euro is about the same as 1 US $).

Designing TV sets was not always an easy task at that time. Look at the
solution that they had to adopt for getting the
proper coupling factor between the sweep generator tube and the mixer tube. The
screen of a 9-pin miniature tube was modified to derive a signal of an
appropriate level.

Below, you see a 75-100W amplifier (model G.274/A) which was
used by I0APV, around 1950, as a modulator in his AM transmitter using a single
PE1/100 in the final stage.

The G.274/A has a push-pull pair of 807s driven by a 6L6G. Two
pre-amplifier stages with 12SL7s. A 5R4GY and a 5Y3GT are used as rectifiers.
The output transformer (Geloso mod. 6054) had been replaced with a modulation
transformer (Geloso mod. 6055) that has the appropriate output impedance for
modulation purposes.

A decade later the Geloso audio amplifiers had a bit more
modern appearance, see model G.215-AN, donated by Joe I0AWJ, using a push-pull pair of EL84s for a nominal output
power of 15 W.

Yes, at that time manufacturers were still serious and declared
real power, not the odd things we see today like "instantaneous peak musical
power". Would you believe I recently saw a car amplifier using two
EL84s, built for nostalgic hi-fi aficionados, advertised as a 200 W amplifier? Geloso did
not even dare to use the "high-fidelity" term, so they just called it
"high-quality amplifier".

All components were made by Geloso, even capacitors, switches
and connectors. Look at those brown matchbox-style electrolytic capacitors.

Geloso, who had a radio amateur license with call I1JGM,
began an ham radio products line in
1952 with the first ham bands-only professional receiver, the G. 207, which was
produced in three versions, i.e. G.
207-AR, G. 207-BR and eventually G. 207-CR.

In 1955 the first "Geloso line" was born, by pairing
a G. 207-CR receiver to the G. 210-TR
transmitter (using a single 807 modulated by a push-pull pair of
6L6Gs). Picture below shows the G. 210-TR (left), the G.
207-CR (right), with a G.208-A general shortwave receiver on its top.

Look at the G.210-TR interior.

The G.210-TR transmitter included the
very first Geloso Variable Frequency Oscillator, i.e. the VFO mod. 4/101. Note that the tube marked 6AU6
looks to be an
octal tube instead of a
miniature one, as it should be. The above picture was probably taken before they decided to change that tube (an
6SJ7?) into the more modern and
better performing 6AU6.

In 1958 a new line came out, i.e. the G. 209-R
receiver (153,500 year-1958 lira, or some 1,650 year-2001
Euro) and the G. 212-TR
transmitter (125,000 year-1958 lira + 395 lira of "tube
taxes", for a total equivalent of some 1,350
year-2001 Euro), still having a single 807 in the final producing 40
W RF, but now with a pair of 807s for modulation.

Picture below
shows the cover page of the Winter-1958 "Bollettino Tecnico
Geloso" describing both the G. 209-R and the G. 212-TR. The
Bollettino was published several times per year since 1932, and
contained a very detailed description of new products (in many cases it
constituted the instruction manual).

In 1962 the last AM/CW-only line appeared: on
the left-hand side of picture below you see my G. 4/214
receiver (double conversion superhet for AM, CW and SSB, but
rather poor on SSB due to its limited frequency stability, the
absence of a product detector and the lack of a fast-attack
slow-decay AGC) and, on the right-hand side, my G. 222-TR AM/CW
transmitter (60 W RF produced by a single 6146 modulated by a
push-pull pair of 807s). Still today, I use this equipment with
satisfaction mainly on the 10-meter AM segment (29.0 - 29.1 MHz): lot of
US contacts!

In 1964, an improved transmitter version appeared (the G. 223-TR), similar to the G. 222-TR but featuring
higher frequency stability by the use of a conversion-type VFO
(mod. 4/105).

By the way, the ham-radio equipment case was also used for other purposes;
below you see model G.1523C, an odd integrated audio amplifier / broadcast receiver
/
switchboard specifically designed for airports, railway stations, jails (hi),
department stores, churches, etc.

All the main items constituting Geloso
receivers and transmitters were also individually sold, so that
one could easily build an home-made transmitter using a Geloso VFO, a Geloso tank coil, a Geloso RF choke, Geloso variable
capacitors, Geloso crystals, Geloso transformers (power and
modulation), and an home-made receiver using a Geloso "RF
group" (everything down to a 4.6 MHz IF), Geloso IF
transformers, etc. etc. Interesting to note that, who knows why, Italian
amateurs using Geloso equipment, when declaring their working conditions, used
to replace the word "Geloso" with then term "la nota casa" (i.e. "the renowned
factory").

In an period when people were much more budget-minded than
today, readily offering the most critical equipment building blocks made
Geloso very popular among amateurs, even in the U.S. where many
hams still today have Geloso equipment or parts hidden somewhere
in the basement. At this regard it should be noted that, in 1963,
Geloso introduced, as part of his line of nuvistor-based VHF
converters, models operating on bands at that time only available
to U.S. amateurs (mod. G. 4/160 for 50 - 54 MHz and mod. G. 4/162
for 220 - 224 MHz).It is also interesting to note that the
Bollettino was bi-lingual, Italian and English: though this would
be normal today, it was not so in the 50ies when only a small
percentage of the Italian population had some command of the
English language. These facts witness that Geloso was
aggressively hitting the U.S. market too.

See the 144-MHz nuvistor converter (model G. 4/161) hooked up to
its power supply (G. 4/159)

and the older ones with conventional miniature tubes viz model
G. 4/151, and model G. 4/152 which had a built-in power supply and costed 38,325
year-1966 lira,
or some 310 year-2001 Euro.

The most popular Geloso loose item surely was
the VFO for the HF range (10 through 80 meters).The
early model was the 4/101, used in the G.210-TR
transmitter, with a 6J5GT oscillator,
a 6AU6 doubler / buffer and a 6V6GT driver.

It was soon followed by model 4/102, in which the 6V6GT was substituted
by a more powerful 6L6G, this change making it
possible to drive two final tubes (e.g. 807s) in parallel instead of just a
single one.

The later model 4/104 instead had just two
tubes, a 6CL6 oscillator and a 5763 driver, both miniature. This VFO, which was
intended to drive a single tube (e.g. one 807 or 6146), appeared for the first time
in the second Geloso transmitter (the G. 212-TR).

In reality, quality was not the best one could expect: switches often suffered from
unstable contacts, VFOs were
generally quite unstable (even the most recent VFO, the
conversion-type mod. 4/105, was not a real rock...). At this
last regard, it is interesting to note the solution that Geloso
adopted for his VHF VFO (144-MHz), the model 4/103.

Actually model 4/103 incorporates two completely
separate oscillators (two 6CL6s), that is a crystal one and a
free-running one (i.e. a proper VFO). A 12AT7 is used to switch the two signals and a 5763
to drive the power amplifier. Below, I report how the summer-1962
issue of the Bollettino justifies the need for two oscillators:

"The aim of having two different
oscillators, the VFO type and the crystal type, is that of using
the former for brief connections (for the research of a
correspondent, etc.), and the latter (having a greater frequency
stability) for a normal connection."

To better understand this, one should remember that at that time (at least in
Italy) 144-MHz operations were
normally crystal-controlled (each amateur in a local area could
easily be identified just by his transmit frequency). So,
breaking in an on-going QSO was an almost impossible task, as
neither of the two hams in QSO would have his receiver
tuned on the breaker's transmit frequency. Geloso offered a
solution to this problem: using the VFO-type oscillator one
could quickly break in the QSO and tell one of the two guys: "Please
listen for me, I am on 144.900!"; then, by means of the
crystal-type oscillator, he could continue the three-way QSO with better frequency stability.

Coming back to the Geloso lines, the SSB era
began in 1965 with the G. 4/225 transmitter (222,000 year-1965 lira, or some
1,825 year-2001 Euro). The transmitter,
having a separate power supply (the massive G. 4/226 at 77,000 year-1965 lira, or some
650 year-2001 Euro), adopted phasing-type SSB. In addition to other more
common tubes, it used a parallel of 6146s delivering 100 W RF
out, three (today hard-to-find) 7360s as balanced modulators, one
6CW4 nuvistor as crystal oscillator, and even an EM87
("magic eye") to permit properly adjusting the transmit
audio level! The case size was still the same as that of the
ancestral G. 207 receiver so, in total, you had to accommodate three real
beasts in your shack. See two of them below (transmitter and matching power
supply)

The new companion G. 4/215 receiver, shown below,
was only produced for a short period and is therefore rather hard to find.

Its more modern case, as well as the new panel colors, were an
early sign that Geloso was going to re-style their ham-radio products. As a
matter of fact the G. 4/215 receiver was soon after replaced (in 1967) by a new
receiver, the G. 4/216, having a smaller case.

The G. 4/216, paired to the new G. 4/228 transmitter
having three 6146s in parallel, was the very last Geloso ham-radio line, Despite
the smaller case, the three pieces (the G. 4/228 had an external supply, the G.
4/229, all having the same case of the G. 4/216) still occupy a remarkable room on
your desk. Noticeably this line, as well as all the former ones,
had no transceive facility, and you so had to zero-beat the
transmitter each time.

The company went out of business in 1972, four
years after John Geloso death.

Their former headquarters located in
Milan via Brenta 29 is now owned by a bank. Picture below was taken before 1960.

After 1972 however Geloso equipment were still on the market
because the trade mark was acquired by other companies, which continued
producing equipment marked Geloso. Below you see a 50-W FM broadcast transmitter
(with a push-pull pair of 6146B in the final) marked Geloso, but built and marketed
by PASO S.p.A., a company also located in Milano.

The rationale behind this product is that, around
1975, there was a huge demand in Italy for FM-radio transmitters, as
almost anyone could freely set-up and operate his own broadcast radio, the
applicable laws being unclear (or perhaps just not enforced?).

By the early 80ies the Geloso trade mark was
still used to label cheap electronic stuff produced in the far east.

By the way, I forgot to tell you
that "geloso" is the Italian for the English word "jealous".

Going back to my Geloso line, I wish to report
you on some of the design oddities which I found in the G. 222-TR
transmitter schematic diagram. First of all, believe it or not,
the front-panel receive / transmit switch (as well as the receive
/ VFO-beat switch) operates directly on the 220 VAC line; in
other words transformers get only powered when one transmits
or wants to zero-beat! Real energy saving, isn't it?

With such an arrangement, switching back from
transmit to receive one would hear a carrier in his receiver
until the power supply capacitors have discharged. To avoid this,
the transmit / receive switch was designed in such a way that,
just at the very middle of its excursion, a resistor was
temporarily grounded to quickly discharge the electrolytic
capacitors. This excerpt of the schematic diagram witnesses that
I am not joking: you can see a 33-ohm 1-W resistor, connected to
the power-supply electrolytic capacitors, getting shorted to the
braid of the coax coming from the receiver socket.

Another candy. The front-panel meter can
conveniently be switched to measure either plate current, or grid
current or AM-modulation percentage, but in the plate-current
position the meter is directly inserted in the high-voltage line,
this meaning that the whole meter (and the switch) is at 750V
potential. Don't worry: the plastic meter lid will protect you
anyway... Here it goes: the resistor marked N. 80164 is the meter
shunt through which plate current flows.

Before leaving this brief tour, please give a
quick look to my Geloso G. 299 (1958), an unusual equipment called
"Oscillofono" having the very plain task of generating
an audible tone on pressing a Morse key (a loudspeaker was not
included). This unit was expressly designed for code training; I
guess it is a pretty rare item. In kit form, its year-1958 price was 13,500 lira
(without tubes), equivalent to about 150 year-2001 Euro.

By means of a front-panel switch one can select
the tone frequency, either 800 Hz, or 1,000 Hz or 1,200 Hz. The
socket marked "Tasto" (the Italian for "Key")
mates to the typical Geloso 3-pin microphone plug. The audio
output on the back panel has two impedances, 3.2 and 600 ohm. The
output waveform looks very good on the scope, a nearly perfect
sinusoid.

What that sturdy box does can today be done by
just a tiny NE555 plus, if you really need more power, an
audio-amplifier IC. The G. 299 instead includes:

a 50 W-class power transformer (made by
Geloso of course);

a big can-type dual electrolytic capacitor (Geloso-made);

a Geloso output transformer;

a Geloso two-winding audio transformer,
the primary of which constitutes the "L" of the
resonating "LC" circuit producing the audio
signal;

two tubes, 12AU7 and 6AQ5, not made
by Geloso but bearing a Geloso sticker (John, if I were
you, I wouldn't trust those tubes manufacturers...).

The world was much simpler than today, but we
enjoyed it anyway, didn't we?

Geloso ham radio equipment

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